Machine telephone switching system.



L. POLINKOWSKY. MACHINE TELEPHONE SWITCHING SYSTEM.

APPLICATION FILED MAR.2, I914. 7 1,137,231, Patented Apr. 27, v1915.

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APPLICATION FILED MAR. 2. 1914- 1,137,231.

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MACHINE TELEPHONE SWITCHING SYSTEM.

APPLICATION FILED MAR.2, I914 Patented Apr. 27, 1915.

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APPLICATION FILED MAR.2, 1914.

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L. POLINKOWSKY. MACHINE TELEPHONE SWITCHING SYSTEM.

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MACHINE TELEPHONE SWITCHING SYSTEM.

APPLICATION FILED MAR.2. 1914.

1,137,231 Patented Apr. 27, 1915.

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vmwx/ Ahuv UNITED STATES PATENT OFFICE.

LIPA POLINKOWSKY, OF BRUSSELS, BELGIUM, ASSIGNOR TO WESTERN ELECTRIC 1COMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS:

MACHINE TELEPHONE SWITCHING SYSTEM.

Application filed March 2, 1914.

To all 107mm it may concern:

Be it known that l, LIIA POLINKOWSKY, a subject of the Russian Emperor,residing at 19 Rue Brialmont, Brussels, Belgium, have invented certainnew and useful Improvements in Machine Telephone Switching Systems, ofwhich the following is a full, clear, concise, and exact description.

This invention relates to improvements in machine telephone switchingsystems, and has to do more particularly with systems in which theextension of the desired connection from a calling line to a called lineis accomplished by automatic switching apparatus directly or indirectlyunder the control of a subscriber at the calling substation. Many of thefeatures to be described, how ever, are not restricted to systems ofthis character, being also applicable, as will be apparent to thoseskilled in the art, to systems of widely varying character, as for example to semi-automatic telephone exchange systems, and also some of thefeatures herein disclosed apply as well to manual telephone exchangesystems.

In British Patents Nos. 26,079/10 and 21,259/11 there are describedautomatic telephone switching systems in which impulses transmitted froma calling station and representing the number of the Wanted line arereceived at the central ofiice by registering devices which thereuponact as controllers to govern the selecting operations necessary toextend the connection to the line represented by such registration.Furthermore, in British Patent No. 21,259/11 there is described a systemand arrangement in which translation takes place in such registering andcontrolling devices whereby, although the controlling mechanism locatedat the substation may be constructed and operated according to onesystem'of notation, the actual selection of the desired line and of thetrunk lines over which it may be reached may take place in accordancewith some other system of notation.

()ne of the principal features of this invention relates to systems oi.the character described in the patents referred to and relates moreparticularly to an improved and novel registering and controllingequipment and means for associating the same with the calling substationand the selectors to be controlled. Most specifically this feature ofSpecification of Letters Patent.

Patented Apr. 27, 1915.

Serial No. 821,896.

the invention involves the use of power driven registering andcontrolling devices in such registering and controlling equipment and ofimproved and novel circuits and arrangements whereby such devices may becontrolled and operated accurately and at high speed to positively andprecisely control the operation of the automatic switching devices to beselectively and accurately set in response to the controlling operationat the called subscribers substation.

Another feature of the invention relates to the connection of aconnecting circuit taken for use by a calling line with a registeringand controlling equipment of the type referred to and involves the useof switching mechanism adapted to quickly and accurately make suchconnection to permit under certain conditions the simultaneous controlof such registering and controlling equipment by the calling subscriberssubstation and the control by such equipment of the selective operationsof a switch over which the call is to be extended.

A related feature of the invention provides for means whereby a ringingtone, by which the calling subscriber will be informed that the calledparty is idle, and that his station is being signaled, is providedassociated with the group selector to which the circuit of the callingsubscriber is first extended.

Other novel features of the invention, such particularly as relate tooperations of various sequence switches (steering switches) used thereinand the inter-operation of such switches will more fully appear from thedetailed description of the invention.

In the drawings, Figure 1 shows the circuits and apparatus of asubscribers line and Fig. 1 the first line finder adapted to extend theconnection of such line when calling; Figs. 2 and 2 illustratediagrammatically the second line finder and the connecting circuitassociated therewith, together with the group selector and otherapparatus associated with such connecting circuit; Figs. 3 and 3"illustrate the circuits and a]')paratus of a final selector; Figs. 4 and4 illustrate the circuits and apparatus of a registering and controllingequipment adapted to be associated with the connecting circuit shown inFigs. 2 and 2, to control the group selector and final selector to theright of Fig. 3, Fig. 4 below Fig. 2,

and Fig. 4 below Fig. 2.

The line finders, group selectors and sequence switches are of typesalready known in the art as illustrated in the British patents abovereferred to, and need not be herein specifically described. Also the'method of showing the sequence switch contacts is well understood, andmention need only be made, that in Fig. 2 the sequence switch contactsof the three sequence switches shown thereon are associated with thesequence switch indicated in that portion of the figure separated fromthe remaining portions by dotted lines. The final selector switchdiffers from the final selector switches of this type previously knownonly by the addition of two extra notches in the interrupter plate ofthe top thereof, between the first 10 notches thereof and the second 10notches thereof. It will be recalled that selector switches of this typehave a capacity of two hundred lines, and the contacts of these linesare arranged in ten levels of twenty lines each. Between the bank of theone hundred lines individual to one hundred, and the bank of linesindividual to another hundred, that is to say, between the first tenlines of each level and the second ten lines of each level there is aspacing plate. In selector switches of this type previously known thespacing between the two banks of line contacts was without effect, asthe interrupter plate at the top of the selector was uncut over theportion thereof corresponding to the spacing plate. In the finalselector switches as used herein, however, there are two notches cut inthe portion of the interrupter plate corresponding to the spacing platefor purposes herein described. That is to say, in selecting a line inthe first set of ten lines on a given level, the interrupter willoperate a number of times corresponding to the number of lines passedover, whereas, in selecting a line in the second set of ten contacts onsuch given level, the interrupter will operate a number of timescorresponding to the number of lines passed over plus two. This will bereadily understood from an examination of Fig. 5 in which the notches arepresent the notches of such interrupter plate corre-' sponding to -thefirst set of ten lines on the given level of the selector; the notches brepresent the notches in such plate corresponding to the second set often lines on such level, and the two notches 0 represent the two extraor additional notches which have been added as above indicated forpurposes hereinafter described.

The invention as disclosed herein will be best understood from adescription of the operation of the system shown.

Assuming that the subscriber at the substation indicated at 120 desiresconnection with the subscriber indicated at 320, whose number is 307, hefirst removes his receiver from its switchhook, therebyclosing acircuitfor the line relay 121 which, on its ener- 30 gization, closes a circuitfor and energizes the pilot relay 122 common to a group of incominglines which appear multipled upon a given group of first/line finderssuch as the one shown in Fig. 1. Relay 122 closes a circuit over thesequence switch springs 104- and 103 for the poweranagnet 1.23 of allthe first line finders of this group which are at this time in idlecondition; that is, whose sequence switches 100 are in first or normalposition. Such idle line finders will, therefore, start in motion,moving their brushes 125, 126, 127, 128 over the terminals 129, 130,131, 132 of the lines appearing in such line finders and testing suchlines in the usual way. As one of them, however, brings its brushes intocontact with the terminals of the calling line, it will find upon theterminal 132 of such line a selectable potential produced by theenergization of the line rethe test relay 135 will be energized over thesprings 102 bottom, 108 top and either the spring 106 -or theinterrupter brush 136..

The energization of this rela 135 closes. through its armature a lowresistance holding winding for itself, the closure of such 0 circuitthrough such winding so reducing. the potential upon the terminal 132that such potential -is no longer selectable, and any other line finderwhose brush 128 comes in contact with such terminal 132 will not All hestopped. The carriage of the or which has thus seized the linefcontinuesin motion, however, until its brushes are pro erly centered upon theterminals of the ca ing line, at, which time thecircuit through theinterrupter brush 136 will be open, and the shunt eing removed fromaround the power control test relay 137, suchrelay will e energized,openin the circuit of the power magnet 123 an closing the circuit of theholdi magnet 138 o ver the springs 105 top and 10 thereby positivelystopping the brush carria in proper position. The energization' 0 ,therelay 137 has also driven the sequence switch 100 out of its first intoEbb - switch 000 out of its its second position. In this movement of thesequence switch a test guard is maintained upon the terminal 13;. andthe seized line through the spring 112 bottom, the spring 102 bottombeing opened as the sequence switch leaves its first position. In thesecond position the spring 110 being closed, the cut-ofi' relay 1.39 ofthe calling line is energized, causing the decnergization of the linerelay 121 and the consequent deiinergization of the pilot relay 122,provided no other line of this group is at this time calling and not asyet been seized by a line finder. The deenergization of the relay 121opens the battery circuit to the terminals 132, and the line now havingbeen seized and being maintained busy, no selectable potential ispossible upon its test terminal 132.

The sequence switch 100, on coming into its second position, hasestablished a circuit over spring 113, the pilot wire, and the spring002 bottom, hack contact of relay 237 and spring 603 top for the powermagnets 226 of the idle second line finders in which the circuitconnected to the first line finder shown appears in multiple. The brushcarriages of such idle line finders, therefore, move the brushes 227,228, 229, 230 over the contacts 231, 232, 233, 231 of the various linesappearing in such line finders.

The sequence switch 100, on coming into its second position, by closingthe springs 10S bottom, 100 top and 107, has placed selectable potentialon the terminal 231 of the trunk line or circuit connected to the firstline finder associated with such sequence switch 100. \Vhen the brush230 of one of such second line finders comes in contact with theterminal 234, upon which this selectable potential exists, theiest relay235 will be energized, the circuit for such relay including the springs003k top, (305 top and either the interrupter brush 230 or the spring606 top. Such relay 235 will, therefore, be energized, closing inparallel to its right'hand winding the low resistanccholding winding,which will so reduce the potential upon the terminal 231 that no othersecond line finder can now seize the line to which such terminal isindividual. The brushes of the seizing second line finder, however, willcontinue to move until when they are centered upon the terminals of theseized line the circuit over the interrupter rush is opened, and, theshunt being thereby removed from around the power-control tcst relay237, such relay is energized to stop the switch in the usual manner byopening the circuit of the power magnet 226 and closing the circuit ofthe holding magnet 238, at the same time driving the sequence first intoits second position by closing a circuit over the spring 607 top.

As the sequence switch 600 leaves its first position, and until it haspassed through its, seventh position, a busy test guard is maintainedupon the terminal 234 by the closure of the spring (310, connectingground to such terminal. As the sequence switch 600 was passing from itsfirst into its second position, the spring 611 was closed sufiicientlylong to drive the sequence switch 200 out of its first position, thecircuit for moving such sequence switch including the spring 202 bottom.This sequence switch comes to rest in its second position.

In position 2 of the sequence switch 000, and in position 2 of thesequence switch 200, the selection of an idle registering andcontrolling mechanism will take place. Before considering thisoperation, however, the various eliects of theseizure of the circuitconnected to the first line finder, and the movement of the sequenceswitch 200 into position 2 will. be considered. \Vhen the test relay 235was energized, the circuit therefore also included the relay 37, tomaintain it encrgized, and relay 137 being energized the sequence switch100 is moved from its second position to its fifth position.

In position 5 the circuit for relay 137 will include the resistance 1-10as well as the resistance 141, but such relay will be maintaincdenergized so long as the spring 010 top is closed.

In position 5 of the sequence switch 100, the spring 110 being open, thecircuit for the cut-off relay 139 now includes the spring 102, the relay135 and the spring 207; the sequence switch 200 now being in the secondposition. In this position also the spring 112 is open is extended overthe springs 210 top and 211 top to the repeating coil 239.

As the sequence switch 600 came into its second position, the springs601 bottom, 619 top, 605 bottom, 606 bottom and 613 bottom were closed.If at this time the sequence switch 700 individual to the connectingcircuit shown is in such position that an idle registering andcontrolling equipment is connected by it to the leads shown, the relay240'will be energized over a circuit including springs 703, 619 bottom,704 bottom, relay 420 and spring 405 of the sequence switch 400individual to such idle registering and controlling equipment. If,however, the equipment with which the leads are connected over suchsequence switch 700 is already busy, the test circuit including therelay 240' of some other connecting circuit will already be energizedover the cirduit including the relay 426 and insufiicieut current willpass through the relay 240 shown, to energize it. A circuit will,therefore, be established over the back contact of such relay 240,spring (313 bottom and spring 702 to cause the sequence switch 700 tomove and it will continue in motion until on closand the circuit of thecalling line ing the circuit from the leads of the connecting circuit tothe leads of an idle equipment the relay 240 is energized, at which timethe circuit over the sequence switch 700 will be opened and the relay237 being energized in parallel with the relay 240 the sequence switch600 will be driven through sequence switch springs 602 top and 607 topfrom its second into its third position. In this position the relay 210and the relay 237 are directly connected over the spring 619 bottom andover the spring 704 bottom, for example as shown, to the starting relay426. This idle registering and controlling equipment is now seized andis inaccessible to any other connecting circuit having access theretountil it has performed its function or has been released by the hangingup of the receiver of the calling subscriber, as will be hereinafterdescribed.

As the sequence switch 600 moved into its third position it closed thecircuit over the spring 009 to drive the sequence switch 200 also to itsthird position. In this position springs 210 bottom and 211 bottom areclosed, and the impulse receiving circuit .from the subscriberssubstation to the registering and controlling equipment is now complete,such circuit being traceable from battery through the stepping relay427, spring 402 of the sequence switch 400, spring 707 bottom of thesequence switch 700, sprin 210 bottom of the sequence switch 200, brush228 and terminal 232 of the second line finder switch, brush 126 and terminal 130 of the first line finder switch over the subs :ibers line andthrough his substation, terminal 129 and brush 125 of the first linefinder switch, terminal 231 and brush 227 of the second line finderswitch, spring 211 bottom to ground and back to battery. This circuitbeing established, and the relay 426 being energized, as beforedescribed the sequence switch 400 is driven out of its first and intoits fourth position.

It will be observed that the calling subscribers supervisory relay 241,which at this time controls restoration and which in position 2 andposition 4 and positions subsequent thereto is directly under thecontrol of the calling subscriber, is energized by the closure of aspring 205.

The apparatus will now await the sending of impulses by the callingsubscriber, such impulses being arranged in'groups corresponding to thecomplement of the digits of the numerical designation of the calledsubscribers station-that is to say, the called subscribers number beingassumed to be 307, the calling subscriber will transmit to the centralstation three series of impulses, the first series comprising sevenimpulses, the second series comprising ten impulses, and the thirdseries comprising three impulses. In each of these series of impulsesthe last impulse sent will be relatively longer than the other impulsesof the series, which other impulses are, in fact, quite short. Thesender by which these impulses are sent may be of any desired structuralcharacter, provided that the impulses are sent in a complementarymanner, and that the last of each of the groups of impulses sent by suchdevice is relatively longer than the other impulses of such group. Asender is diagrammatically shown capable of accomplishingthe necessaryfunctions, and in which the setting of the sender roduces no impulse inthe circuit. The impulses as produced in the system as disclosed areinterruptions of the circuit.

The system herein disclosed is. for clearness shoun only as a 1000 linesystem. In such a system there will be five groups of final selectors,each accessible to 200 lines thereof, and the group selectors used willhave only five of the ten banks thereof utilized, one bank of contactsbeing connected to the trunk lines of the group of final selectorsindividual to one group of 200 lines, another connected to another groupof final selectors individual to another 200 lines, and so on. Inaccordance with the translating system disclosed herein, the selectionin the group selector of the trunk. line leading to the group of lineshaving the proper hundreds digit is such that if the 100s digit of thedesired line is zero or one, the tripping spindle of the group selectorwill be adjusted to release the proper set of brushes on the brushcarriage by the movement of such spindle one step or stage. If the 100sdigit of the desired line is two or three, such spindle will be movedthree steps or stages. If the 100s digit is four or five, the spindlewill be moved five steps or stages. If the 100s digit is six or seven,such spindle will be moved seven steps or stages, and finally if the100s digit is eight or nine, such spindle will be moved nine steps orstages. Qf ,course, it will be understood that if the system is for morethan 1000 lines that the intermediate steps or stages, that is, second,fourth, sixth, eighth and tenth will be reserved for use when a trunkline. is desired leading to the groups of selectors having access totholines of such second thousand. In a 1000 line system as hereindisclosed, the trunk lines may be, and it will, be assumed, are,connected to the alternate levels of contacts in such group selector. Itwill be further understood that by properly rearranging the trippingteeth upon the tri ping spindle, the five levels and termina s which areused may be arranged, if desired, adjacently to' each other, so that thefirst level will be selected by a single step of the trippin spindle,the second evel by three steps 0 such spindle, third lavolby five stepsof such spindle, and so on. Further more, if preferred, the arrangementof the lines of the subscribers upon the final selectors may be soarranged that the trunk line leading to a corresponding group of 100 ineach of the two thousand lines accessible through a group selector willbe selected in the 'same level of such group selector, such arrangementresulting in the selection of a line whose 100s digit is zero in eitherthousand by one step of the tripping spindle of the group selector, :1line whose 100s digit is 1 by two steps of the tripping spindle, and soon. As shown, however, the arrangement of the lines and the selection inthe group selector will take place as first above described. Anoperation, therefore, of the subscribefis sending mechanism to send the100's digit 3 will produce seven breaks in the circuit, hcreinbeforedescribed, including the stepping relay 427, the last of such breaksbeing relatively longer than the others of the group. Upon the initialenergization of the stepping relay 427 a circuit was closed by itsarmature over the spring 408 and the back contact of the changeoverrelay 1 28, including the lower winding of the 100's register 429. Thiscauses the energization of the power-magnet of such register and itmoves until when midway betWCUI'l its zero or normal position and itsfirst position, its local positioning or A spring 471 is closed. At thistime a circuit is closed over the front contact of the relay I26 andsuch positioning spring through the upper winding of this register. Thetwo windings of the register are differentially wound on the powermagnet thereof, so that when a circuit is closed through both of saidwindings, or when there is a circuit through neither of said windings,such register will stop; whereas, when a circuit is closed through butone of said windings the register will move. The register 429, havingtherefore been brought to rest between its zero and first positions,will await the opening of tln circuit through its lower winding at thefront contact of the stepping relay 4-27 before moving further.'lherel'ore, as the result of the first impulse or interruption in thecircuit in the operation of the subscriber's sending mechanism, and theconsequent deenergization of the stepping relay 427, the register willmove into its first position. the circuit of the up per winding thereoibeing closed through the positioning spring (71. Upon the cessationo}-the first impulse, the relay 427 is again energized, and the register429 is driven to a position intermediate of its first and secondpositions, correspondingly in response to the second impulse it will bedriven into its second position. Therefore,

as seven impulses are bein receiyed, the seventh impulse W111 drive t eregister 429 into its seventh position. As this impulse is a longer onethe stepping relay 427 will be deenergized snfliciently long for itsarmature to close at its back contact andtspring 413 a circuit for theslow operating changeo er relay 428 and energize the same. Thischangeover relay, opens the circuit of the register 4-29 at itsright-hand armature, in order to prevent any false operation of suchregister, and closes at its left-hand armature a circuit over spring*101 for the sequence switch 400, driving such sequence switch into its6th position. The 100s register has now been set. and it may proceed tocontrol selection in the group selector. For this purpose the outgoingsequence switch 450 shown to the right of .Fig. 4?, and whose springsare all to the right of the dotted line, has been started by the closureof the spring 407 bottom as the incoming sequence switch 400 passesthrough its 5th position. Before, however, describing the selectioncontrolling operation initiated by the movement of the outgoing sequenceswitch 450, further registering operations will be described.

Upon the rci stablishment of the transmitting circuit, and theconsequent eucrgization of the stepping relay 427, the circuit throughthe lower winding of the 10s register 430 will be energized in the (3thpositionof the sequence -l00 over the spring 109 top. The group ofimpulses now being sent in, comprisin r ten impulses, (the zero digit;lbeing sent), t e tens register will be move to, and come to, a stop inits tenth position precisely in a similar manner as that in which the100s register was set. The last impulse of this group being a relativelylonger one, the changeover relay 428 was energized and the sequenceswitch Hi0 driven into its-eighth position, the 101s register +30thereby being removed from association with the stepping relay, and theunits register 431 being placed under the control of such relay by theclosure of the spring 109 bottom. The closure of the controlling circuitincluding the stepping relay 927 and its intcrruption three times tosend the digit '7 will cause the units register 431 to move into itsthird position in the manner now well understood, and the final impulsebeing a long one, the sequence switch "lUO will be driven out of itseighth position by the encrgization of the changeover relay 4-38. In itsninth position the incoming switch 400 will remain until at theconclusion of the selection controlling operation it is started inmotion to its normal position b a circuit closed by the outgoingsequence switch 150 in returning to normal over the spring 407 top.

The registers have now been set to properly control the selectioncontrolling operations in accordance with the numerical designation ofthe desired subscribers line; the 100s register has been moved into itsseventh position, the 10s register has been moved to its tenth positionand the units register moved into its third position. As the incomingsequence switch 400 reached its ninth position a circuit was closed overthe spring 412, and the spring 206 bottom, to drive the sequence switch200 out of its third into its fourth position, in which position thesupervisory relay 241 is again placed under the control of the callingsubscriber, and the sending circuit from the calling substation is openat the springs 210 bottom and 211 bottom.

The outgoing sequence switch 450 of the registering and controllingequipment, when it was moved from its first position as the incomingsequence switch 400 passed through its fifth position as abovedescribed, continued in motion until it reached its fourth position.Inpassing from its first to its second position, a test was made by thespring 459 to determine whether the 100s digit of the number registeredwas odd or even; it having been found to be odd, the hundreds r gisteris in its seventh position, seven impulses having been sent by thecalling subscriber operating his sending mechanism for the digit 3, acircuit was closed for the translating relay 432. It will be observedthat the spring 474 of the 100s register is closed in the followingpositions; only a few of which, for clearness, are indicated upon thedrawings:

The relay 432 was therefore energized, closing by its right-handarmature a locking circuit for itself including the spring 455 top, andsuch relay will be maintained energized until the sequence switch leavesits ninth position.

As the sequence switch 450 passes through its second position theclosure and subsequent opening of the circuit of the power magnet of the100s register over the spring 458 bottom will drive such register oneadditional position that is in this case into its eighth position. Alsoas the sequence switch 450 passes through its third position thetranslating relay 432 being locked up a circuit will be established overthe spring 460 top, left-hand armature of such relay and spring 461bottom, to drive the 100s register 429 from its eighth into its ninthposition.

On coming into its fourth position the se quence switch 600 beingalready in its third position, the fundamental circuit from theregistering and controlling equipment is closed to the group selectorshown on Fig. 2. This circuit includes the line relay 242 of the groupselector, and the selection controlling step ing relay 433 of saidequipment, both 0 which relays will be energized. This circuit alsoincludes the spring's612, 473, 457 and 611 bottom.

The energization of the relay 242 drives the sequence switch 600 intoits fourth position over the spring 614, in which position the circuitfor the tripping spindle'power magnet 243 is closed and the trippingspindle starts in motion. In moving from position 3 to position 4,sequence switch 600 makes no changes in the fundamental circuit.

As the relay 433 was energized coincidently with the energization oftheline relay 242, it closed the circuit over the spring 458 top for thelower winding of the 100s register 429; the register, therefore, moved ahalf of a position, that is, until the closure of the circuit throughits upper winding and the positioning spring 471 thereof is closed. Asthe tripping spindle of the group selector began to move itintermittently closed a circuit to ground, such circuit being soconnected to the fundamental circuit that when it is closed the relay433 will be shunted and denergized, though the line relay 242 ismaintained energized. This deiinergization of the relay 433 will takeplace once for each movement of the tripping spindle one step or stage.Upon the deencrgization of the relay 433 the 100s register again movesuntil it comes into its tenth position, from which position it will bemoved to a position intermediate between its tenth and eleventhpositions, when the relay 433 is again energized as the tripping spindlecomes into its set position to ,trip the first set of brushes of thegroup selector; in the continued motion of the tripping spindle a seconddenergization of the relay 433 takes place and the 100s register ismoved into its 11th position, to be moved again into a positionintermediate between its eleventh and zero positions, when the shunt isagain removed at the tripping spindle. I

The next closure of the earth connect-ion at the tripping spindle, andthe consequent third deenergization of the relay 433 drives the 100sregister into its zero or normal position. In this position the spring473 is open and, consequently, not only will the relay 433 remaindeenergized when the connection to earth is broken at the trippingspindle, but also the line relay .242 will be deenergized, both' thefundamental circuit and the branch circuit to ground being now open. Assoon as this occurs, the circuit for the tripp n spindle power magnet243 is open at the from contact of the line relay 242, and-the trippingspindle is brought to rest. Such tripping spindle, having moved threesteps or stages, is now in position to release the third set of brusheson the brush carriage of the group selector, as it will he recalled thata trunk line leading to the group of final selectors in which thedesired line appears is to be found in the third bank or level of suchgroup selector.

As the 100's re a tcr came into its zero or normal poatioii, if theincoming sequence switch 100 is in its 9th position-that is, it s andunits registration is complete-a circuit .will be closed including thesprings 4'56, 472 and 410 to drive the outgoing quence switch 430 intoits (3th position, in which it is ready to control tens selection assoon as an idle trunk line to a proper final selector has been found andseized in the group selector, as will be described. It the incomingsequence switch 100 is not as yet in its 9th position, the outgoingsequence switch 450 wi l remain in its 4th position, moving into its 6thposition as soon as the sequence switch 400 reaches its 9th position.

'hen the line relay 2l'2 stopped the move ment of the tripping spindleof the "[OHP selector, it also closed a circuit oi er liacli contact andthe spring (302 top, back coir tact and armature of the relay 237, whichis decncrgized after the sequence switch (300 left its 3rd position, andspring 07 bottom, to drive the sequence switch 600 into its 5thposition.

In the 5th position a circuit will be estahlished for the group selectorpower magnet 214, including the spring 603 bottom, the hack contact andarmature'ot relay 237, seqi'ience switch spring (362 top and the hackcontact and armature of the line relay 242. The brush carriage of thegroup selector, ther 'ore, will begin to move in its first movement,causing the proper set of brushes to be released in the movement pastthe said tripping spindle and then causing such released brushes 24 5,2th and .517 to make contact with the various sets oi ontacts in. theselected level. t o long as the test rusli J17 nnikos cont": t with thetest terminal ol' trunk lines which arc. already cn rac'ed, ll!siillieiciit potential will he found there-on to cncrQiZ c the relay 333due to the fa t that lhc low res stance winding of a relay z-iam'spi'uidiirc to the relay J35 oi" some ot ie group selector is alreadycoiiiicci d iii th terminal inultiplcd to such lW-t terminal. As soon.however. as the brushes conic iii contact with ol' lWllllllll indi idualto an idle. lruiil; linc. full pot ntial wi l he l'ouiul on th lc--tterminal thereof, and a circuit ill l t ("ltldlfllii'l For the tct relay2257i ((t('lii lli; i'i'oin l uil'cry at liiial selector over tl-ospring" ill l-ottoiii, pring; H top, the lcl't winding, ol' the relay 331, test (fullductor ol the seized trunk liuc, test brush 247 of thegroup selector, right-hand high resistance winding of the test relay235, spring (305 top, power control test relay 237 and spring coo top toground. The test relay 235 will be energized, but the relay 237 will notbe energized owing to the shunt therearound existin o\'cr theinterrupter brush 244.

The energization of the relay J closes a low resistance circuit throughits lelthand winding parallel to its right-hand winding, which soreduces the potential upon the test terminal of the trunk line that thetest relay 235 of no other group select r. the brushes of which come incontact with the terminals of such line, will be energized. As soon asthe brush carriage, which is continued in motion, properly centers the bushes upon the terminals ol the seized line. the shunt circuit throughthiinterrupter brush will he open and the relay 531' ill be energized.The encigg'ization of this relay will open the circuit for the powerlllil illiit 15H and close the' circuit tor the hohlinu' magnet over thespriuga hum top a d T top, so that the brush carriage oi the groupselector will he properly and accurately ,-toppcd in the welllinownmanner, The can ation of the relay L' li' has also closed a circuit forthe sequence switch Will to drive, such sequence switch into its lllposition. in this position of the sequence switch too the fundamentalcircuit is connected through from the final selector to the registeringand controlling equipment, and the closure of this circuit at this timedepends upon whether the outgoiiig sequence switch 430 has reached its6th position.

When the sequence switch was driven out of its fourth position upon thecompleti n of the hundreds selection controlling opm'alion it moveddirectly into its sixth position hut in passing through its ii th poition the momentary chruii'c of the spring ill-'3 bottom has driven thetens registcr into its clci'ciitli osition in now (he wclllltillil'rlliiul manner. \V HE': no: the i'undai'llllilill circuit i siXtlipo-iiioii oi the quence \J-Ciu h iinrludthe n role .i select r,

- top, roup selec- "i lilo sp i no ii. .riii. inc i ifjjilfia tion oftin rile drives th qucnce snit h 1 inti f}. 'iill'i po---iiioo hy theclosur of tin llil' llt over the spring 303 top. in which mitionthicircuit for the trippingspindle power magnet 333 is closed o er thcspringiilrj hottoin and the trout conta t ot' the relay 332. The trippinspindle will (hw -upon begin to ii'iove. The energi- Zation at this timeof the relay 4533 has closed a circuit over the spring 462 top to movethe tens register one-half of a position from the position in which itwas set as described.

It will be recalled that the lOs digit of the desired line is zero and,therefore, such line is to be found in the first bank or level of thefinal selector. It will therefore be necessary that the selectioncontrolling operation of the final selector should be terminated whenthe tripping spindle has moved one step or stage and is in position torelease the set of brushes corresponding to the first bank set or levelof contacts. It will also be recalled that the tens register was set bythe subscriber in its 10th position and subse' quently moved to itseleventh position. When, therefore, the tripping spindle at the finalselector moves its first step or stage, the shunting of the relay 433 inthe wellknown manner drives the tens register into its zero or normalposition. This movement of the tens register immediately opens thefundamental circuit at the spring 483 of such register, so that when theshunt circuit through the tripping spindle is opened both the relay 433and the relay 332 are denen gized. At the same time the closing of thespring 482 of the tens register closed a circuit including the springs411,- 482 and 463 top to drive the outgoing sequence switch 450 into its8th position ready to control units selection, and the fundamentalcircuit which has been maintained open between the 6th and 8th positionsof such sequence switch will there await its second closure at the finalselector.

Immediately upon the decnergization of Y the line relay 332 as justdescribed the movement of the tripping spindle is stopped, it being newin position to trip the first set of brushes on the brush carriage, andthe sequence switch 300 is driven from its second position to come torest in its 4th position.

As the outgoing sequence switch 450 of the registering and controllingequipment moved through its seventh position upon the termination oftens selections the momentary closure of the spring 454 moves the' unitsregister one additional position so that when the sequence switch stopsin its eighth position" and again closes the fundamental circuit theunits register is in its fourth position. The closure at this time ofthe fundamental circuit again energizes the relays 332 and 433, but thistime in the 4th position of the sequence switch 300 and the 8th positionof the sequence switch 450. In the 4th position of the sequence switch300 the energization of the relay closes a circuit over the spring 306top from the brush carriage power magnet of the final selector, and suchbrush carriage begins to move. In the initial movement of the brushcarriage, the proper set of brushes (in this case the first set) istripped as the carriage passes the tripping spindle.

In the subsequent movement of the brush carriage the brushes 334, 335,336 sweep over the sets of terminals individual to the lines multipledto this bank or level of contacts. For each movement of such brushes toa set of terminals the interrupter device 337 closes a circuit to roundfrom the fundamental circuit over I; e springs 313 top and 315 inthe'well-known manner, such circuit to ground as is well understoodshunting the relay 433 while maintaining the relay 332 energized.

Upon the energization of the relay 433 and its subsequent intermittentdeelnergiza-v ti-on due to the shunting action of the contacts of theinterrupter 337 at the final selector, the units register will bestepped in the well understood manner, one full position for eachenergization and subsequent de'e'nergization of the relay 433. At theend of eight of such operations of the relay 433 the units register willagain be in its normal position, the selected brushes of the finalselector at this time being about to make contact with the 8th or No. 7set of contacts of the bank or level to which they are individual. Itwill be recalled, however, that since the desired line is located in anodd hundred, the particular line desired is to be found in the secondhalf of the final selector, and it is therefore necessary that theselecting operation should not terminate at this time. For this reasonthe fundamental circuit is not opened at this time at the spring 493 aswould be otherwise the case, a shunt being maintained about such spring,such shunt including the spring 460 bottom, left hand armature of thetranslating relay and the spring 461 top.

It will be recalled that the relay 432 was locked up when the sequenceswitch 450, in passing from its first to its second position, tested thecondition of the 100s register 429, and on finding it in a positioncorresponding to an odd hundred, completed the circuit for thetranslating relay 432. 'Ihe fundamental circuit not being open at thistime, the brush carriage at the final selector will continue to moveuntil the units register 431 has made a complete revolution as a resultof such movement. This means that the units register will take twelveadditional steps. It will now be seen for what purpose the twoadditional notches in the interrupter plate of the final selector areprovided, as hereinbefore described. To reach the contacts of thedesired line after the units register has first reached its normalposition would otherwise produce only ten deenergizations of thestepping relay 433, and,

consequently, only ten steps by the units register.

Since it is necessary that the units register should come into its 70tion in order to lertion. it is n: steps he i l'tlili tzi l'o: twoadditional notches are cut rupter plate of the liml silw to: to

'l hcrci'orc, utter the relay 133 has heen epcrutwl two tional times,and so. i the final elector with the Tih set of teen-oi. hal'i or rangeof tin t flimfiijal 0f the final selecton the again he in its l i 'iiLiigar-whom.

As the units hi? position withoutsii-opiusr. as scribed. circuit wasclosed over the spring" 4 33 bottom to (hire t of its 8th and into thiscircuit lining only maintained momentarily by the spun-J The sequenceswitch stopped in it. When now the unilr; comes a second time into itsnornml {it the shunt around the Spring '39.} thew it springs MO huitwnztlll t immediill the infrihr the spring 43' quence switch its 10thposition.

in}: opened at the "hi1 top, the fundim'ienial eirt ately opened.producing the Ki in the manner well and iii?- to terminate select Theunits re understood. of the Y izi final selector. ing into its normalposition a returns to its n' rn'nil witiozi. 1.l0"('i!1(?llt in ,o:'i.-.sin thro' clos s :i circuit at spring turn the .-"-:e:'nwz1cr switch-14 lt suouhl he also not scournee switch 410. on lea ing it:

the locking" r:-

3 bottom to re tion opener lating relay V ing been selected. theSt'l'Yit ng and controlling equipi'nent longer required. for this conneetherefore. aS-the sequence sn'itth 9th position the spring 4-0 cuit torthe relays 420 an euit had been 'substi innlly estalilishci'l sequenceswitch 400 The relays 426 and Q 1 i opened the (ir- (1 210, WhichCittutetl for the one oi over the spring lo?) a i s left its first,posit (l are thereto? tlevnei" elay 426 is de'e'nergized asrleiinergized and by the re armature closed a circuit to nce switch 600from its .ifiitll position. This is the through position of thissequence switch. \ement, however, the cont line it v'iil iuniaulml a othe sequrnw so itch 5M! leaves its tin? position. s the seo r H. snitchlemurs from its fourth to itfi th position. the spring: ill-t t=; i;opeu l ar l 5H hottoni is closed. l r." niainwl PHLlfliZt'ii. lioth 'i,n flii! :ludetl in the i a i .25. H ted over the.

t \ontrol test 1 von: the spring 307 morning 5 utter with a high .iiuz:ot' the test rein 3M).

.1115 {)Hoitinli tlu'rtot'. If in this i ill. r19 m; :5 high hand thenormal otel 5: i aet (criminal lid in i :11! now. either aw l" i-illine. as will cur ninmicr. the te t relay 1.

' 1. 3i;i}sf ti. i hat the mini that such relay is eonse wntiy cnrs'ji'awt. t, closes over its armaur. a -zrcni. through its lowresistance left i t a: l, the ,v relay 339. in pan finding. which willii of the test terminal 1: it will t st has) in rs in liili it appears.w t eoex the [twisty 333 Zlltt when the seouence switch 5300 comes intothe 5! find circuits elmeo om and the other it: position.

relay 312, to more it into its tenth position, in which pns.-'ion. andalso in the eieventh position a rireuit ill he Found closed to mo in itinto its teeii th "I"; *"Xth position ot' "a tmr: i. g

palates for a 'RZL'Y to dri e the sequence switchthrough its sixthposition, which is, as shown, an idle position, whether the desired lineis found idle or busy, the spring 317 is provided.

The twelfth position of the sequence switch 300 is the ringing position.In this position ringing current is projected over the called line bythe closure of the springs 310 bottom and 311 bottom.

As the sequence switch 300 passed through its eighth position, the trunkline leading to its final selector was short circuited by the closure ofthe spring 309 bottom. This causes the momentary energization of thesupervisory relay 248, which by the attraction of its armature drivesthe sequence switch 200 into its eighth position. This would cause thesubscriber to receive the busy tone by the closure of the springs 212bottom and 213 top, except for the fact that almost immediately after asthe sequence switch 300 passes from its eleventh into its twelfthposition, the spring 309 bottom is again closed energizing the relay 218 to drive the sequence switch 200 into its eleventh position. In thisposition of the sequence switch 200, the springs 212 top and 213 bottombeing closed, the subscriber receives the distinctive ringing tone, andwill continue to receive such tone so long as the sequence switch 300remains in its twelfth position.

vSo long as the called subscriber does not respond, insufficient currentwill pass over the ringing relay 343 to energize it. As

- soon, however, as the path for direct current is closed at thesubscribers substation, by the removal of his receiver from itsswitchhook, the relay 343 will be energized and drive the sequenceswitch 300 into its thirteenth position. In this position the circuit isclosed through from the battery and repeating coil shown in Fig. 2 tothe called subscribers substation, and the relay 218 is thereforeenergized, driving the sequence switch 200 out of its eleventh and intoits fourteenth position.

The sequence switch 100 being in its fifth position, the sequence switch200' being in its fourteenth position, the sequence switch (300 being inits seventh position, and the sequence switch 300 being in itsthirteenth position, the calling subscriber and the called subscriberare now connected, each subscriber being supplied with transmittercurrent from the battery shown in connection with the repeating coi1239.Conversation may now take place Disconnection-Upon the termination ofCOHVClStttlOl'l, one or both subscribers return 9 their receivers totheir-"respective switchbooks thcrcb o )enin': a circuit over while thesupervisory relays 241and'248 are maintained energized. Assuming thatthe called subscriber first restored hlS receiver to its swit'chhook,the deenergization of the relay 218 closes a circuit over the spring 203and 209 bottom, to drive the sequence switch 600 out of its seventhposition and into its eighteenth position. In this movement the sequenceswitch 600 closed in its 8th position a circuit over the springs 609 and202 top, to drive the sequence switch 200 back to its normal position.On coming into its 18th position the sequence switch 600 established theusual restoring circuit for the brush carriage of the group selector,and such brush carriage moves until the brush 244 of the interruptercomes in contact with the normal segment, at whichtime circuit is closedover the spring 618 to energize the relay 237 which stops the movementof the brush carriage in the usual manner and drives the sequence switch600 into its normal position.

As the sequence switch 600 left its 7th position, it opened at thespring 610 top the circuit of the relay 137 at the first line finder.This relay thereupon, being deenergized, drives the sequence switch 100from its 5th into its 9th position. In the 8th and 9th positions of thissequence switch a circuit for this relay is again established,

provided the calling subscriber has not restored his receiver to itsswitch hook, which includes the spring 108 bottom, the spring 111, thesubstation circuit and the spring 112 top. The sequence switch 100 willtherefore stop in its 9th position and remain there until the subscriberopens the circuit to direct current at his substation by replacing hisreceiver upon its switch hook. As soon as this occurs, the relay 137will again be deenergized and drive the sequence switch 100 back to itsfirst or normal position. It will be observed that the cut-01f relay 139is controlled through the 7th position by a circuit including the spring102 top, and in the 8th or 9th position by a circuit including theresistance 199 and the spring 110. This transfer of control isaccomplished before the circuit of the cut-off relay 139 was opened atthe spring 207.

As the sequence switch 600 left its 7th relay 332. The energization ofthis relay drives the sequence switch 300 out of its 13t position intoits 10th position. On coming into its 16th position, the circuit at thecalled subscribers substation being already opened. the relay 332 iswithout current and therefore is decnergized, driving the sequenceswitch 300 into its 18th position. In this position of the sequenceswitch 300 the usual circuits are established to restore the switchcarriage of the final selector to i i (1. I'M/3:1

and A 30111 =1"?! suite? 500 thmug ii's fit 1 and 6th positions, R1263":Hm,

I n shml'id be found busy, insm'fivient potcrx'ial Wili J; upon the t sttez'n'i'imil 349- tn rmwill amp, and the restm'ntien of the: bm.

carriage 0f the. selenium will take 311643 0W"? i 4' and 'i'm 'k i ammiw and bad :-:prmg 3C6 (i that H 9 bottom was k-"Hy min i inm its 9thm i umi {5m calling sub i m" 21w may cendiiion "film: the brush cm.- "itm'v 2w aches its n01"- be energized u-mzz] g mp-iii? of 'i' ncc switchHi position. being owned swim 51 leaves switch .300 TE; is sequence{i011 and ihc xvii] remain ii: r0- ,(u'i hook when H'Qatiflh of the sugimme switch 900 11h) its 11th p0- is 9th positiun 1 0W1 URL? back con-5* 'd, ition 01" the Hi0; iiijt'iliTfZiZflii0 0|? iii? mime Hi0cricrgimvw min i253, and the ww izod and the inwming soqnvnco n dirvctlyinto its a from inimum position it w; H1 tinm \Fhen sequence awitch itsninth Dositiun, the sequence will M: driwm from 1' third him. as has bmmhereim The sewence sv itvli 2,00 hm driven i fo ifs ehfi'nfh (10511131NF 1 circuit m'cr the (it the supervisory relay 241, pant-ion the. groupselecmr ivmi;

